Refrigerator compressor



March 6, 1962 J. R. PLAYLE 3,023,590

REFRIGERATOR COMPRESSOR Filed June 29, 1959 2 Sheets-Sheet 1 F/Gfl.

Inventor JACK ROGER PLAYLE yww A Home March 6, 1962 J. R. PLAYLE 3,023,590

REFRIGERATOR COMPRESSOR Filed June 29, 1959 2 Sheets-Sheet 2 Inventor JACK ROGER PLAYL E 3,023,590 REFRIGERATOR COMPRESSOR Jack Roger Playle, Wembley Park, England, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed June 29, 1959, Ser. No. 823,456 Claims priority, application Great Britain July 18, 1958 8 Claims. (Ci. 62196) This invention relates to refrigerator sealed motorcompressor units in which the compressor discharges refrigerant into the inside of the unit casing prior to entry into the condenser; and also to refrigeration systems incorporating such units.

The object of the invention is to obviate or minimise the bursting of the casing by high pressure due to continued operation of the motor and compressor at low intake pressure arising from a blockage in the refrigeration system. Under these conditions, the mass of refrigerant which is drawn into the compressor each cycle is so small that the load on the motor is insufficient, despite the high discharge pressure of the compressor, to actuate a motor overload cut-out device. The blockage is likely to arise, for example, in the expansion valve or capillary restrictor, if a leak occurs in the refrigerant circuit and moisture-laden air enters the system.

The object is achieved by means of a distortable member, preferably a disc valve member, which is located between the interior of the casing and the suction side of the compressor and which ruptures or flexes so as to permit refrigerant from the casing to enter the compressor if the pressure difference exceeds a predetermined value.

When the high pressure refrigerant 2O enters the suction side of the compressor, the compressor, since it is by-passed, begins to idle and continued operation of the compressor does not therefore result in a further increase of refrigerant pressure in the casing. The load on the compressor, immediately after the valve member has flexed or ruptured, initially increases abruptly, since the compressor is suddenly filled with a greater mass of refrigerant, and then decreases to a low idling value. The initial load increase is usually sufficient to actuate a conventional motor overload device to stop the motor.

Preferably the valve member is arranged to replace the valve normally incorporated between the suction line and the interior of the casing for the purpose of opening the former to the latter during the precharge evacuation of the system: thus the disc valve member preferably performs the two functions of prevention of excessive pressure build up in the casing and precharge evacuation relief of the refrigeration system.

The valve member is preferably on the compressor side, that is downstream, of a one-way inlet valve to the compressor. Thus if the member should rupture or flex the inlet valve closes and so prevents high pressure refrigerant from entering the suction side of the refrigeration system.

The scope of the invention is defined by the appended claims; and how it may be performed is hereinafter particularly described with reference to the accompanying drawings in which:

FIGURE 1 is an axial section through a unit according to the invention and shows the remainder of a refrigeration system diagrammatically;

FIGURE 2 is a section on the line IIII of FIGURE 1; and

FIGURE 3 is an enlarged view of a part of FIGURE 1.

The sealed compressor unit comprises a casing 2, a squirrel cage electric motor 4, and a compressor 6.

The stator 8 of the motor is bolted to a frame 12, and the frame 12 is secured to the compressor 6 by bolts ice which screw into the base of the casing 2 to hold the compressor in position within the casing.

The compressor 6 is formed by three plates bolted together. The upper plate 14 has an upwardly pro ecting boss 16, in which the rotor shaft 18 of the motor 4 is journalled. The centre plate 20 has a cylindrical chamber 22 which is coaxial with the shaft 18, and carries a slidable divider block 24 which is spring biased radially inwards. A circular impeller 26 is rotatably mounted on an eccentric portion 28 of the shaft 18, and its periphery is engaged by the block 24, thus forming the usual crescent shaped space. The lower plate 30 has an opemng 1n which the bottom end of the rotor shaft 18 is journalled.

An axial inlet passage 32 in the lower plate 30 (FIG- URE 3) connects a suction pipe 34 (FIGURE 1) from an evaporator 36 to the chamber 22 on the suction side of the divider block 24. Communication through the passage 32 is controlled by a one-way disc inlet valve 38 which opens to admit refrigerant into the suction side of the chamber.

An axial outlet passage 40 is formed in the lower plate 30 on the side of the divider block 24 opposite to the inlet passage 32. A one-way outlet valve (not shown), which opens to permit the flow of compressed refrigerant from the compression chamber 22, is mounted in this passage which is connected to a superheat removal coil 42 which in turn is connected to the interior of the casing 2 (FIG- URE 1) so that the compressor 6 discharges compressed refrigerant into the casing. The compressed refrigerant flows from the casing to a condenser 44 through an expansion valve 46 to the evaporator 36, whose outlet, as mentioned above, is connected to the inlet suction passage 32.

A radial passage 43 (FIGURE 3) is formed in the lower plate 30 and communicates with the axial inlet passage 32 on the suction side, that is the downstream side, of the one-way disc inlet valve 38. A one-way rupturable disc valve member 50 is, according to the invention, mounted in the radial passage 40, and is arranged to open freely to the right (FIGURE 3) when the pressure in the casing 2 is less than the pressure on the suction side of the inlet valve 38 in the axial inlet passage 32. This occurs during precharge evacuation of the refrigeration system.

Thus, in normal use, the disc valve member 50 in the radial passage 48 opens to enable the suction side of the refrigerant circuit, that is the evaporator 36 downstream of the expansion valve 46, to be evacuated.

It is ruptured or flexed radially inwards when the pressure in the casing reaches a certain value to permit refrigerant within the casing 2 to enter the suction side of the compressor; the one-way disc inlet valve 38 in the passage 32 then closes so that the high pressure in the casing 2 is not transmitted to the suction side of the system. When the valve member ruptures a conventional overload cut out device incorporated in a motor starter relay 52 is actuated to stop the compressor motor 4. Thus further pressure build up in the casing is prevented.

The diameter of a typical disc valve member 50, which ruptures when the pressure is about 600 pounds per square inch, is /8, its thickness is .0045" and the di ameter of the valve seat is The disc itself is made of mild steel sheet. It is held in position by means of a spring clip 54 which is held in an axial opening which intersects the radial passage 48.

I claim:

1. A sealed motor compressor unit for a refrigerator, comprising a sealed casing, a refrigerant compressor mounted in said casing, an electric motor mounted in said casing and connected to drive said compressor, passageway means by means of which said compressor discharges compressed refrigerant into said casing, inlet passageway means by means of which low pressure refrigerant is conveyed from outside said casing to said compressor, a pressure relief passageway means between said inlet passageway means and the interior of said casing, and a valve member in said relief passageway means which opens when the pressure in said inlet passageway means is greater than the pressure in said casing and, which is distorted when the pressure in said casing exceeds the pressure in said inlet passage by a predetermined amount and which then permits refrigerant in said casing to enter said compressor.

2. A sealed motor compressor unit, comprising a sealed casing, an electric motor mounted in the casing, said motor including a rotor, stator, and shaft on which said motor is mounted, a refrigerant compressor, said refrigerant compressor including three plates secured together, the centre one of said three plates having a circular compression chamber, said shaft being journalled in the end plates of said three plates, a circular impeller rotatably mounted on an eccentric portion of said shaft within the compression chamber, a divider block slidable in said centre plate and resiliently biassed into engagement with said impeller, axial refrigerant inlet passageway means in one of said plates communicating with said chamber on one side of said block, a one-way inlet valve in said inlet passageway means, transverse passageway means in said plate connecting said inlet passageways means and the interior of said casing, a disc valve member mounted in said transverse passageway means and adapted to rupture when the pressure in said casing exceeds that in said inlet passageway means and to open when the pressure in said inlet passageway means exceeds that in the casing, axial refrigerant outlet passageway means located in one of said plates on the opposite side of said divider block to said inlet passageway means and communicating with the interior of said casing, and an overload device operative to stop said motor when said disc ruptures.

3. A sealed motor compressor unit, comprising a sealed casing, an electric motor mounted in the casing, said motor including a rotor, stator, and shaft on which said rotor is mounted, a refrigerant compressor, said refrigerant compressor including three plates secured together, the centre one of said three plates having a circular compression chamber, said shaft being journalled in the end plates of said three plates, a circular impeller rotatably mounted on an eccentric portion of said shaft within the compression chamber, a divider block slidable in said centre plate and resiliently biassed into engagement with said impeller, axial refrigerant inlet passageway means in one of said plates communicating with said chamber on one side of said block, a one-way inlet valve in said inlet passageway means, a transverse passageway means in said plate connecting said inlet passageways means and the interior of said casing, a disc valve mounted in said transverse passageway means and adapted to rupture when the pressure in said casing exceeds that in said inlet passageway means whereby said motor is overloaded and to open when the pressure in said inlet pas sageway means exceeds that in the casing, axial refrigerant outlet passageway means located in one of said plates on the opposite side of said divider block to said inlet passageway means and communicating with the interior of said casing. I I

4. A sealed motor compressor unit, comprising a sealed casing, an electric motor mounted in the casing, a refrigerant compressor, said refrigerant compressor including three plates secured together, the centre one of said three plates having a circular compression chamber, a circular eccentrically and rotatably mounted impeller drivable by said motor within the compression chamber, a divider block slidable in said centre plate and resiliently biased into engagement with said impeller, axial refrigerant inlet passageway means in one of said plates communicating with said chamber on one side of said block, a oneway inlet valve in said inlet passageway means, a

transverse passageway means in said plate connecting said inlet passageway means and the interior of said casing, a disc valve member mounted in said transverse passageway means and adapted to rupture when the pressure in said casing exceeds that in said inlet passageway means, axial refrigerant outlet passageway means in one of said plates communicating with the interior of said casing, and an overload device operative to stop said motor when said member ruptures.

5. A sealed motor compressor unit, comprising a sealed casing, an electric motor mounted in said casing, said motor including a rotor, stator, and shaft on which said rotor is mounted, a refrigerant compressor, said refrigerant compressor including three plates secured together, the centre one of said three plates having a circular compression chamber, said shaft being journalled in the end plates of said three plates, a circular impeller rotatably mounted on an eccentric portion of said shaft within the compression chamber, a divider block slidable in said centre plate and resiliently biased into engagement with said impeller, axial refrigerant inlet passageway means in one of said plates communicating with said chamber on one side of said block, a one-way inlet valve in said inlet passageway means, a transverse passageway means in said plate connecting said inlet passageway means and the interior of said casing, a disc valve member mounted in said transverse passageway means and adapted to rupture when the pressure in said casing exceeds that in said inlet passageway means, axial refrigerant outlet passageway means in one of said plates communicating with the interior of said casing, and an overload device operative to stop said motor when said disc valve member ruptures.

6. A refrigeration system comprising an evaporator, a superheat removal coil, a condenser whose outlet is connected to the evaporator inlet, and a sealed motor compress-or unit, said unit comprising a sealed casing connected to the condenser inlet, an electric motor mounted in the casing, a refrigerant compressor drivable by said motor, said refrigerant compressor including three plates secured together, the centre one of said three plates having a circular compression chamber, said shaft being journalled in the end plates of said three plates, a circular impeller rotatably mounted on an eccentric portion of said shaft within the compression chamber, a divider block slidable in said centre plate and resiliently biasscd into engagement with said impeller, axial refrigerant inlet passageway means in one of said plates connecting the outlet end of said evaporator and said chamber on one side of said block, a one-way inlet valve in said inlet passageway means, transverse passageway means in said plate connecting said inlet passageway means and the interior of said casing, a disc valve member which is in said transverse passageway means and which is distorted when the pressure in said casing exceeds that in said inlet passageway means by a predetermined amount to permit refrigerant flow from said casing into said inlet passage way means and opens when the pressure in said inlet passageway means exceeds that in said casing, axial refrigerant outlet passageway means in one of said platescornmunicating with the interior of said casing through said superheat removal coil, and an overload device operative to stop said motor when said disc valve member ruptures.

7. A sealed motor compressor unit for a refrigerator,

comprising a sealed casing, an electric motor within the casing, a rotary refrigerant compressor mounted within the casing and drivabie by said motor, passageway means connecting the outlet from the compressor to the interior of the casing, inlet passageway means for conveying refrigerant from the outside of the casing to the compressor inlet, said compressor having a branch passageway conmeeting said inlet passageway with the interior of said casing, a one way valve in said inlet passageway means,

a one way disc valve member in said branch passageway which opens when the pressure in said inlet passageway means exceeds that in said casing and which is ruptured when the pressure in said casing exceeds that in said inlet passageway means by a predetermined amount so as to permit refrigerant in said casing to enter said inlet passageway means downstream of said inlet valve.

8. A refrigeration system comprising an evaporator, a superheat removal coil, a condenser, and a sealed motor compressor unit, said unit comprising a sealed casing, an electric motor within the casing, a refrigerant compressor mounted within said casing and drivable by said motor, passageway means connecting the outlet from said compressor through said superheat removal coil to the interior of said casing, inlet passageway means for conveying refrigerant from the outlet of said evaporator to the compressor inlet, said compressor having a branch passageway connecting said inlet passageway with the interior of said casing, a one way valve in said inlet passageway means, a one way disc valve member in said branch passageway which opens when the pressure in said inlet passageway means exceeds that in said casing to permit evacuation of the suction side of said system and which is distored when the pressure in said casing exceeds that in said inlet passageway means by a predetermined amount to permit refrigerant to enter said inlet passageway means so as to increase the load on said motor, and an overload device operative to stop said motor when 10 said load is so increased.

References Cited in the file of this patent UNITED STATES PATENTS 15 2,396,459 Dana Mar. 12, 1946 2,738,657 Jacobs Mar. 20, 1956 2,794,323 Rataiczak et a1 June 4, 1957 2,904,971 Kosfield Sept. 22, 1959 

